Polyimides are also useful as components which require excellent thermal, electrical and/or mechanical properties. For general discussion of polyimides preparation, characterization and applications see Polyimides, Synthesis. Characterization and Applications, L. Mittal, ed Plenum, NY 1984.
Polyimides based on pyromellitic dianhydride and various organic diamines are disclosed in U.S. Pat. No. 4,485,140 to Gannett et al (E.I. DuPont de Nemours and Co.).
Polyimides based on diamines such as 2,2'-di-(p-aminophenyloxy)-diphenyl and various dianhydrides are disclosed in U.S. Pat. No. 4,239,880 to Darms (Ciba-Geigy Corp.).
Harris et al. in U.S. Pat. Application Ser. No. 07/315,327, has disclosed the preparation of soluble polyimides based on 3,6-diarylpryomellitic dianhydride and various diamines including the diamines of the present invention. The polyimides taught in this reference lack the clarity of the present polyimides and are more expensive to prepare and lack the versatility of the polyimides described herein.
However, the polyimides derived from the above cited references lack consistency in satisfactory properties to be used a high clarity, low dielectric constant coating materials or in high compression strength fiber or fabric application.